1. Field of the Invention
The invention relates to an apparatus and method for feeding sheets from a stack. More specifically, the invention relates to a sheet feeder for printers and copy machines capable of feeding sheets at rates in excess of 1200 pages per minute.
2. Description of the Related Art
In related art devices such as copy machines, sheets of copy paper are fed off of a stack using a drive mechanism that starts and stops to feed each sheet. The drive mechanism generally includes a vacuum plenum for drawing a sheet against a feed belt that starts and stops between each successive sheet feeding. While such related art devices have proven successful and reliable, since the feed belt must start and stop between each successive sheet, the sheet feeding speed is limited. Sheet feeding rates in excess of 400 pages per minute (ppm) are uncommon in prior art devices. However, the current trend in the printing arts is towards copiers and printers that reliably operate at high speeds, such as 600 ppm and faster.
In addition, in related art devices, the motor that, drives the feed belt must constantly start and stop. Not only is this inefficient, but it also causes undue wear on the sheet feeding motor.
Further, many prior art devices include complex and costly registration hardware for timing and aligning the copy paper sheet with the position of a tone image on the photoreceptor at a transfer location.
An object to the invention is to provide a sheet feeding apparatus capable of reliably feeding sheets at high rates of speed.
A further object of the present invention is to provide a sheet feeding device that minimizes wear on the sheet feeding motor.
An additional object of the present invention is to provide a sheet feeding device that eliminates the need for costly and complex registration hardward.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.